15" wheel fitment on 3/4 ton?

[Russ72C10]

Fair warning - this may be a silly question!

My '84 K20 has what appears to be 16x7 (doesn't look like 8") wheels... 8 lug. Here's the thing. I would almost rather have 15x10 wheels instead - as tires (which I've yet to buy, but want 35x12.50s) seem to be easier to find and cheaper for the 15s. Are there any issues with running a 15" on a 3/4 truck? Anything that needs to be done to slip 'em on? I remember hearing something that's a PITA, but not sure what.... Darn old age! (whew, almost 26!)